Fire-damp indicator



F. H. SGHRUDER & H. BECKER.

FIRE DAMP INDICATOR.

APPLIOATION I'ILEI) NOV.16, 1910.

Patent-ed Apr. 18, 1911.

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GERMANY.

FIRE-DAMP INDICATOR Specification of Letters Patent.

Patented Apr. is, ism.

Application filed November 16, 1910. Serial No. 592,603.

To all whom it may concern:

Be it known that we, FRIEDRICH HEINRICH SoIInooEn and HEINRICH Bnonnn, subjects of the King of Prussia, German Emperor, and residing at Rccklinghausen,Germany, have invented certain new and useful Improvements in Fire -Damp Indicators, of which the following is a specification.

Our invention relates to apparatus for indicating fire-damp.

For indicating combustible gases, e. g. tire-damp, it is well-known to utilize-the heat produced by such gases in catalytic bodies, 6. g. spongy platinum. Apparatus has been made heretofore, in which the heat produced in spongy platinum influences an electric circuit by varying the resistance of a conductor. Although these devices can indicate the presence of gases, they can however not be employed in practice, e. g. in mines, becausethe heating of the spongy platinum always leads to the ignition of the explosive mixture.

A primary object of our invention is to provide apparatus of this type, to which this defect is not attached. To this end, we do not employ spongy platinum pure,but mixed with bad conductors of heat. It has been found that the ignition of the explosive gases, 6. g. firedam-p, is hereby prevented. A mixture of spongy platinum with kieselguhr and asbestos fibers has been found particularly suitable.

One illustrative embodiment of our invention is represented by way .of example in the accompanying drawing partly in vertical section and partly diagrammatically.

In the device illustrated the heat produced in the spongy platinum by the gases influences in known manner the resistance of an electric conductor, and the changes in the current caused'thereby are indicated by a measuring instrument. It has been found that, in such an arrangement, the Indications of the instrument can be made proportional to the percentage of combustible gases.

Referring to the drawing, a designates a vessel, having porous or perforated side walls, containing a wavy resistance wire I).

This conductor 5 is embedded in the mixture 0 of spongy platinum and bad conductors of heat, the mixture being preferably so arranged that the outer layers 03 thereof contain absolutely no spongy platinum. The variations in the current produced by the battery e are indicated by the instrument f and may be recorded by the same.

We claim 1. In means for indicating the presence of combustible gases by means of heat produced by spongy platinum in contact with the gases, the combination with a mixture of spongy platinum and. bad conductors of heat,, of an electric conductor embedded therein.

2. In means for indicatin thepresence of combustible gases, the com inatlon with a mixture of spongy platinum with kieselguhr and asbestos fibers, of a conductor of elec-' tricity embedded therein.

3. In means for indicating the presence of combustiblegases, the combination with a source of current, and an indicating instrument connected with one pole thereof, of a mixture of spongy platinum and a plurality of bad conductors of heat, and a resistance wire having one end connected with said instrument and the other end connected with the other pole of the source of current.

4. In means for indicating the presence of combustible gases, the combination with a source of current, and an indicating instrument connected with one pole thereof, of a mixture of spongy latinum and a badconductor of heat, and a resistance wire having one end connected with said instrument and the other end connected with theother' pole of the source of current.

FRIEDRICH HEINRICH SOHRilllER. [11.8.] HEINRICH BEGKEE- IL. 8.]

Witnesses GHAs. J. WRIGHT, IVAL'I'ER Vonnnoor. 

